3*(1+1/3)=4
2*(1+1/5)=2.4
1/2-1/3=1/6
1/6*4=2/3
(1-2/3)/(4+2.4)=5/96
2/3+5/96*4=7/8
3/(2+3)=3/5
3/5-(1-7/8)=19/40
190/(19/40)=400(米)
3*(1+1/3)=4
2*(1+1/5)=2.4
1/2-1/3=1/6
1/6*4=2/3
(1-2/3)/(4+2.4)=5/96
2/3+5/96*4=7/8
3/(2+3)=3/5
3/5-(1-7/8)=19/40
190/(19/40)=400(米)